I think it would have been a great idea. At least I'm very happy with the phonetic writing system finnish has. It makes learning to read much easier and is one of the reasons why finnish school kids do well in international level.

carnegie was wrong thinking that it would be especially useful to foreigners because: "The foreigner has the greatest difficulty in acquiring it because of its spelling."
spelling is easy for foreigners. we learn words from dictionaries and textbooks. pronouncing the words is difficult tho.

phonetic alfabets would probably lessen the differences between accents (or dialects) only problem is that which accent would we choose for the phonetical basis of this great simplified spelling.